Gate actuating mechanism for motion-picture machines



Jan. 3, 1950 K. BRENKERT GATE ACTUATING MECHANISM FOR MOTION-PICTURE MACHINES Filed Aug. 31, 1948 INVENTOR. XHRL BRENKERT BY WE HTTGRNEY,

Patented Jan. 3, 1950 GATE ACTUATING MECHANISM FOR MOTION-PICTURE MACHINES Karl Brenkert, Detroit, Mich., assignor to Radio Corporation of America, a corporation of Delaware Application August 31, 1948, Serial No. 47,037

The present invention pertains to a novel actuating mechanism for motion picture machines and particularly projectors.

It has been customary in such machines to employ rather heavy springs for holdin the gate closed. Consequently a correspondingly heavy and rather costly mechanism was required to open the gate and hold it open. The manual;

force necessar to operate such a gate assembly is an inconvenience and annoyance to the operator, for otherwise he would be able to operate the gate with one or two fingers of one hand while using both hands simultaneously for threading the film across the open gate, and to close the gate while holding the film in the proper position.

The principal object of this invention is to dispense with the aforementioned heavy springs and to provide a mechanism that can be operated under the conditions described. Another object is to provide a relatively simple and inexpensive gate actuating mechanism of the character set forth.

In the accomplishment of these objects, an operating arm is extended from the gate, and a lever pivotally mounted on the frame structure is attached to the arm. The rear end of the arm is sloped and is in engagement with a fixed pin on the frame, when the gate is in closed position.

A spring connecting the arm to a point on the frame structure wedges the sloped end against the pin to maintain the gate in closed position. The lever has a cam connection to the arm for the purpose of causing the arm to ride over the pin in opening the gate. When the opening movement has been completed, the spring has crossed the pin and now holds the gate positively in the open position. The spring has suflicient strength for the purposes described, yet it permits operation of the mechanism by finger pressure on the lever.

The sloped end of the arm is preferably formed on a lengthwise adjustable section of the arm. In this manner the overall length of the arm is adjustable to compensate for wear of the parts, I

Figure 4 is a detail elevation showing a different position;

8 Claims (01. 88-17 screws I9 and 20.

. 2 Figure 5 is an end view on the line 5-5 of Figure 1, and

Figure 6 is a section on the line 6-6 of Figure 4. Reference to these views will now be made by use of like characters which are employed to designate corresponding parts throughout.

In Figures 1, 3 and 4 is shown a fixed frame member I which may be the internal partition of thehousing of a motion picture projector. On the member I are suitably supported two horizontal guide rods 2 and 3 for a purpose that will presently appear. A slide 4 is mounted on the rods 2, 3 and constitutes a portion of the gate assembly which includes the usual gate member 5 fastened to the slide in any suitable manner as by means of one or more screws 8. A lens tube I is mounted adjacent to the gate member 5 in the usual manner.

As in prior constructions, the gate assembly is adapted to be moved into close proximity to an aperture plate 8 and to be moved away from the aperture plate at times for threading a film between the gate and the plate. an arm 9 is pivotally attached at ID to the lower portion of the gate assembly, preferably the slide 4, and extends rearwardly or along the tube I. For the purpose of actuating the arm 9, a hand lever I I is pivotally mounted on the member i and below the arm in any suitable manner as by means of a boss I2 attached to the member I and carrying a pin I3 on which the lever is fulcrumed. The lower end of the lever is formed as a finger piece I at the lower end and is forked at I5 at the upper end to receive the arm 9. A pin I6 passed through the fork also passes through an inclined or cam slot I I in the arm 9, for a purpose that will presently appear. The arm 9 includes, as a portion or extension thereof, a plate I8 attached to its rear end by a pair of The screws pass through over sized holes 2I in the piece I8 to permit an adjustment of the overall length of the arm by setting the piece I8 lengthwise of the member 9,. after which the screws are tightened.

A horizontal pin 22 mounted on the member I engages the rear end of the arm when the gate is in closed position as shown in Figure 1. A coil spring 23 has its lower end fastened on a screw.

24 mounted on the member I in substantial vertical alinement with the pin 22. The upper end of the spring is engaged on a small screw 25' For this purpose r a fi'xed frame member "and a' gate assembly slid The rear end of the arm 9, II is sloped downwardly and forwardly at 21 for engagement by the pin 22 when the parts are in gate-closing position. The spring 23 causes a wedging of the slope 21 against the pin 22 to hold the gate closed with the force of the spring. When it is desired to open the gate or" withdraw it fronnthe plate 8, the lower end I of" the lever I l i's swung-"forwardly to exert a rearward pressure of the pin IS in the cam slot II. Because of the slope of the: slot II, the arm assembly is raisedsufliciently tobring its lower edge in riding relatiomonttiie pii'i 22, as shown in Figure 4. At the same time, the spring 23 crosses to the other sitle of the pinjli and maintains the open position'sh'owrrin i ig ure 4.

As previously indicated, it hassbeen. customaryto employ strong springs to hold the gate closed,

and consequently a heavy and somewhat -c'om*-- plicated device was required to hold the gate open under the pressure'of: thestitong: springs: The manual force required for this operation is.dis-' tu-rbing: to. the operaton. since he: wouldzlilre to actuate the gate with the finger of one: hand said assembly and lying substantially parallel to the sliding direction of said assembly, an operating lever mounted on said member and pivotally attached to said arm, the rear end of said 5 arm being sloped, a pin on said member and en- 111' said pin, said spring being positioned to cross said pin onmovementof said lever and arm to gateopening position.

4. A gate actuating mechanism for motion picture machines comprising, in combination with .129 wiixed f-i'ame member and a gate assembly slidably mounted thereon, an arm pivotally attached to said assembly,v an operating lever mounted on said member and having a cam connection to said ,arinadapted to move said arm vertically on movement of said lever in the gate-opening direction,

a' plate adjustable: lengthwise on the rear portion ofi said" arm;- the rear: end of said plate being. sloped, a pin on said member and engagings'aid sioped end when the: gate: assembly is in: closed while-using:both hands:simultaneous]yrinitiiread-- a n andflaniexpafldedispriflg haviiigritsrends.

ing the film; The: relatively'light' construction' herein disclosed; permits convenient opening and closing" of: the gate'rin the manner described; The: lengthwise: adjustability of: the plate It" on the:

attached respectively to said member and" arm and positioned to wedge said end against said pin;

55 A g'a'te' actuatingmechanism' foii'motionpic-- mama arm m m r 9 p rm diustment of the sc ture: machines comprising, in combination with overall length to compensate for: weanirregu larities:inmanuiacture'and assembly,,.and to: reg, ulate the pressures of thessprmgili in'the gate closing: position; The spring; L althoughr-reiativelw a: fixed fria'm'e member and agatea's'sembiy' slid-- ably mounted" thereon, an armipivotally attached tsp-said assen iblyi,- a lever mounted on said mem ber a nd pivotally att'a'che'dtosaid arm, a plate h isr'sufiicient-toholdzthereateoneniOre-105w? adjustable lengthwise on-the rear portion of'sa'id with? adequate force.-

Aithonglr a specific embodiment of: the inven tion has been illustrated and describedgiittwill be understood that-various alterationsiin' the details of construction"manbe-made:withoutdeparting: Qwsaid'member and engaging, saidesmpgd endiwhen,

ating lever: mounted onsaid member and piv 5 otally attaclied' to said arm; the rear end ofsa-id armbeing sloped, a" pin on-said' member and-em gaging said" sloped endwhen the" gate assembly" isin closed position; and anexpandedspringliav ingits ends attached respeetiv'efyto said mem her and arm and positioned w wedge saidend against said pin;

2.- A- gate actuatingmeclianism for motion-pic ture-macliines comprising; combination with" ablymounted thereon, an*arm' pivotally attached to said assembly, an operating l'ever"'niounted om said i memberand havingacanr connection t'o'- said arm adapted to movesaimarm vertically-on movement o'f said lever" in tiie-gatemp'ening d'irectionythetreari eridi of said arm being sloped; ai pin: onisaicl' member: and engaging" said" sloped end \vhenlt'heigate'zassem'bly is -inzlclosed position and'anrlexpanded springvhavmgiits ei-ids attached respectively to said member and? arm and posi tioned I to 'wedge' said" end: against sai'di 3; A gatet actuatingxmechanisnrforlmotiompic-=' tureemachinesi comprisingc in:combinationi with aii fixed frame: membersandizaagate assemblwslidablit arm; tl'ie'rear'end" of said plate being-'sloped downwardly and'to'ward the "pivot pointof'the arm, an expanded spring havingits ends; attached re-' H spectively to said' memb'er'and arm; and'a pin on thegate'assemblyis in closed position, said" spring being positioned to cross said pin on movement of said lever and arm: to"ga'te-ope'ning position;

6: Aigate"actuatingfme'c'hanism' formation pictiue'machines' comprising; in combination with a fi'xed'framelmember and a gate assembly slidably mounted'threoman arm pivotall attached to" said assembly; an operating. lever. mounted on said member and having acam connection to said arm adapt'edto move said arm vertically on move ment of said lever in the gate-opening direction;- a plateadjustable length-Wiseonthe rear portion of" saidarm,- the. rear end of said: plate being sloped, .a pin on saidmember and engaging. said slopedliend when-the gate assembly is in closed:

position, and arr-expanded spring having .its ends attached respectively" to said memberandarm and positionedto- Wedge said end: against said- 0;. pin.

7 A=gate aotuating mechanism-for motion picture machines comprising; in" combination with a-fixed-iralme memb'er'an'dagate assembly slid ably mounted thereon; .an': arm pivotally "attached: 6:5; to: said assembly a lever mounted on said' mem-- here, said-'- arm having a. cam slot at which said" lever is attached to the arm, said slot b'e'ingisliaped toraise said arm on movement of saidlever in the gate-opening direction, the rear end' of said armbeing sloped downwardly and toward" the pivot point of{the-.-arrr'i, an expanded spring Having its endsattached respectively to said member and arm; and axpinon saidmember and 'engaging said smpediend: when-. the gate -assembiy is in closed mounted thereon, an arm pivotally attacliedatoa position, said spring being positioned to cross'said pin on movement of said lever and arm to gateopenin position.

8. A gate actuating mechanism for motion picture machines comprising, in combination with a fixed frame member and a gate assembly slidably mounted thereon, an arm pivotally attached to said assembly, a lever mounted on said member, said arm having a cam slot at which said lever is attached to the arm, said slot being shaped to raise said arm on movement of said lever in the gate-opening direction, a plate adjustable lengthwise on the rear portion of said arm, the rear end of said plate being sloped downwardly and toward the pivot point of the arm, an expanded spring having its ends attached respectively to said mem- KARL BRENKERT.

REFERENCES CITED The following references are of record in the file of this patent:

FOREIGN PATENTS Country Date Germany Nov. 21, 1927 Number 

